weedman



Feb- 21, 1956 J. A. WEEDMAN FRACTIONATION PROCESS Filed Aug. 21, 195]RECYCLE UREA ELEVATOR BVM" y? A7' TORNEYS United States Patent QFRACTIONATION PROCESS v John A. Weedman, Bartlesville, Okla., assignorto Phillips Petroleum Company, a corporation of Delaware ApplicationAugust 21,' 1951, serial No. 242,311;

1s claims. (ci. 25o-96.5)

This invention relates to a process for the fractionation of a mixtureof organic compounds. In one of its aspects it relates to a process forthe fractionation of a mixture of organic compounds having similarcarbon atom configuration. In a specific embodiment it relates to aprocess for the resolution of a mixture of hydrocarbons having similarcarbon atom configuration.

In the prior art it is known that urea will react with certain straightcarbon atom chain organic compounds to form a solid adduct. It is alsoknown that thiourea will form a solid adduct with certain branchedcarbon atom chain organic compounds. In accordance with this knowledge,there has been provided a process for the separation of organiccompounds, which process permits the separation of ,a class of compoundshaving one type of molecular arrangement from a class of compoundshaving a different type of molecular arrangement. Thus, straight chainhydrocarbons can be separated, individually or as a class, from branchedchain and/or cyclic hydrocarbons independently of the boiling points ofthe compounds being separated. This process dependsfupon the peculiarproperty of urea, CO(NH2)2, which permits it to form an adduct withorganic compounds having straight carbon atom chains and yet not to forman adduct with branched chain or cyclic organic compounds. Thus, in sucha process it is' possible to separate n-octane from2,2,4-triinethylhexane, isooctane, or branched chain hydrocarbonsirrespective of the boiling 'point'sfr Also, straight-chain hydrocarbonscan be readily separated from aromatic hydrocarbons, for example benzeneor toluene, orfrom th,e cycloparayns, irrespective of the boiling pointsthereof.

While urea forms adducts with organic compounds having straight carbonatom chains, thiourea, CSUIHia,A forms adducts with certain organiccompounds having branched or cyclic carbon atom chains. Thus,theadductforming property of thiourea permits a ready separation of suchcompounds from organic compounds having straight carbon atom chainssince the latter do not forrn adducts with thiourea. The adducts thusformed with either thiourea ot urea are readily recoverable by ltrationor other suitable means from the organic compounds that form no adductswith urea or thiourea, and then the adducts can be dissociated torecover 'the urea or thiourea, as the case may be, and theadduct-forming organic compounds. This dissociation is ordinarilycarried out by treating the adducts with warm water, the waterdissolving the urea, and the adduct-forming organic cornpounds areseparated from the aqueous phase as a separate liquid or solid phase.Thus, although the prior art' processes provide a ready means for theseparation of a class of compounds having one type of moleculararrangement from a class of compounds having a different type ofmolecular arrangement, it is often desirable to separate one group ofcompounds within a single class from another group of compounds withinthat same class. Thus, it would appear to beL highlydesirable to possessa process which could fractionate a mixture of 2,735,843 Patented Feb.Z1, 1956 ICC 2 straight carbopwatoifnl'chain organic compounds intovarious fractions thereof o a 'mixture of branched chain organiccorii'pou`ds l htofr'ac'tions thereof without resorting lto the high tee'ratur'es incident to an ordinary fractional distillat'iofn process. v

r Therefore, it isanfobj'ec't of, this invention to provide aprocess'for theI ffaction'ation of a mixture of organic compounds. Itisanbtherobject of this invention to provide a process for thefractionatofb'f a mixture comprised of a class of orgarii'c compoundshaving one type of molecular arrangeineritintoitwo' or more fractionsthereof.

lt isi'stillfanothr 'obi'ectf of this invention to provide a process for'the :frajc'ionation of a mixture composed of straight carboniatom'chaincompounds into fractions thereof without resorting"V to vtemperatureshigh enough to cause `any `defconrposition of said compounds.

lt is yet another object'of this invention to provide a process for lthefractionationvr of a class of organic compounds liaving 'asingletype ofcarbon atom conguration into various fractions thereof by the selectiveformation and decompoisit'ioii'bfadd'cts thereof with urea or thiourea.f

Adiiiiioaijbjeeir this invention win become apparent to onerskilled inthe art upon reading the disclosure and cliris in conjunction with theattached drawings wherein iFignres land 2 illustrate preferredembodiments ofthe Aprocess of this invention.

It has'ibe'n foundl that a mixture comprised of two or more organiocompounds which are of the same molecular typofc'arbn atomconfiguration, e. g. straightchain, so' that they'will form van adductwith an amide selected fiorntl'iel Agiioiip consisting of urea andthiourea, can'gbe separated' into l'fractions thereof according to thestability'oftl'i dduci's'whieh they form with the amide employed byifo'itz'titin'g'v the mixture with an amount of said :amidev-'wi'i1'i:h2-'iis"ii-isiificient Vto form an adductwithfallfoi""theiigaiiic compounds in said mixture. It'ha's alsorifft'tidt'iiat th''mre lstable adduct-formii'1g""orgahic compoundswillnot only form an adduct witli thamir'lebjit will?displace Ie'ssstable adduct-forming organic inpn'tllrtlie adducted state. Thus, when asufficientanrffffmiiie is employed to form an adduct'witfrtiilfo'rstaible adduct-forming organic compounds only;A there "willresult, irrespective of any prior adduct formation between the amide andthe less stable adductfriiliig compounds, an adduct of the more stableadduct-forming 'organic compounds to the relative exclusion of the less"stable adduct-forming compounds.

-I have found `thatysutix an admixture of organic compounds`which"`r'e'f`eapable of forming a solid adduct with said amide andwhich are of the same molecular typeff carbon"toincfonguration can beseparated into fct-insoidinig'ttHe' stability of the adducts which theyVforin with-Ithemid 4employed by passing them into a moving bied-of'said amide and refluxing the discharge end of said 'moving bed of amidewith the more stable adductjforiningmixganic compounds in an amountsttiucientf'toca ubstantial displacement of any adduciedless staufiaddnct-forming organic compounds fromfthe'solid afld'ctstatcandthereby forni an adduct more pui-e withfrespeci to the more sta-bleadduct-forming organic compounds. The less stable adduct-forming organiccompounds can be passed counter-currently to the moving bed of amide to,in turn, displace still less stable adduct-forming compounds from theadducted state. As a'resultfthe least' stable adduct-forming organic`compoundswill be 'concentrated as a liquid fractionation at the inuentend of'the moving bed of amide and can brwithdrawn tlerfomf lf'desired.organic compounds wichform adducts of intermediate stability can bewithdrawn from the bed at corresponding intermediate points therein.

Still further, I have found that this same type of mixture of organiccompounds having the same type of molecular carbon atom configurationcan be fractionated by passing it into a moving bed of the selectedamide and then by maintaining a temperature differential across the bedwith the discharge end of the bed at a temperature sufficiently high todissociate any adduct formed therein and the inuent end of the bed at atemperature sufficiently below said high temperature that adductformation can occur therebetween, the more stable adductforming organiccompounds will form a solid adduct with the amide which moves into thehot end of the moving bed. At this end, the adduct will be decomposed ordissociated and a portion of the more stable adduct-forming organiccompound can be recovered while sufficient of the remainder can bereturned to the moving bed to act as rellux to displace less stableadduct-forming organic compounds from the adducted state thereby drivingthem toward the cooler end of the moving bed. These less stableadduct-forming compounds can be removed from said cool end as a separatefraction and other fractions which form adducts of intermediatestability can be withdrawn from the moving bed at correspondingintermediate points therein. A diluent which is preferablynon-adduct-forming is passed countercurrently through the moving bed toact as a heat carrying medium and as a solvent for the displaced organiccompounds` A general description of the types of compounds which do anddo not form adducts will be given in order to illustrate better theapplicability of the process of this invention.

In general, an adduct can be formed by contacting a straight carbon atomchain organic compound with urea either with or without an activatorsuch as methanol or water or the like present. The straight chaincompounds can comprise one or more of a normal alkane or alkenehydrocarbon having from 6 to 50 carbon atoms in the molecule, such ashexane, the hexenes, heptane, the heptenes, octane, the octenes, nonane,the nonenes, decane, the decenes, and progressively higher molecularalkanes and alkenes including those having 50 carbon atoms. The straightcarbon atom chain compound can also be a primary alcohol having from 6to 50 carbon atoms being saturated or unsaturated and thus correspond incarbon atom configuration to the straight-chain hydrocarbonsabove-mentioned. Urea will also form adducts with such straight carbonatom chain compounds as primary amines having 6 to 50 carbon atoms permolecule, mereaptans having from 6 to 50 carbon atoms per molecule,ketones having from 3 to 50 carbon atoms per molecule, esters of organicacids having from 5 to 50 carbon atoms per molecule, and organic acidshaving from 4 to 50 carbon atoms per molecule.

Urea does not form adducts with branched carbon atom chain compoundsnot' with Cyclic or aromatic organic compounds such as isohexane,methyl-octanes cyclohexane, benzene, toluene and cymene.

Thiourea forms adducts with branched carbon atom chain organic compoundsbut does not form adducts with straight carbon atom chain organiccompounds nor with aromatic compounds. Thus, adduct-forming power ofthiourca is substantially opposite to that of urea in that the thioureaforms adducts with branched-chain organic compounds and not withstraight-chain organic compounds. Thiourea can form adducts with suchcompounds as the branched carbon atom chain alkane and alkenehydrocarbons having from 5 to S0 carbon atoms in the straight-chainportion of the molecule and from l to 20 carbon atoms in a side chain.Illustrative of such compounds are isohexane, ethyl hexane, isohexene,isoheptane, isoheplenc, ethyl heptane, ethyl octane, trimethyl nonanc,ctc. Thiourea also forms an adduct with a secondary or tertiary alcoholhaving from 5 to 5() carbon atoms in the straight-chain portion of themolecule and l to 20 carbon atoms in a side chain; and with a ketonehaving from 5 to 50 carbons in the straight-chain portion of themolecule and from l to 20 carbon atoms in a side chain. Thiourea alsoforms an adduct with various cycloparains having at least 6 carbon atomsin the cyclic portion of the molecule and which can or cannot containvarious side chains containing one or more carbon atoms per chain, suchas cyclohexane, cycloheptane, cyclooctane, cyclononane, methylcyclohexane, dimethyl cyclooctane, etc.

Activators which can be employed in my process to activate theadduct-forming reaction are preferably lowboiling oxygenated hydrocarbonderivatives such as methanol, ethanol, acetone, methylethyl ketone,propanol, secondary butyl alcohol and the like. Other known activatorswhich will not chemically interfere with the process and which areeasily separable from components of the mixture being resolved can beemployed.

When employing the process of my invention it is pre- [erred that theorganic compounds in the mixture to be resolved all be members of ahomologous series such as straight-chain hydrocarbons, alcohols, etc. Inthis manner the resolution will take place according to the molecularweight of the compounds, or according to the number of carbon atoms inthe molecule. However, my invention should not be construed as solimited since it is applicable to the resolution of a mixture of organiccompounds of similar carbon atom configuration not of the samehomologous series. In this later instance the resolution will take placeaccording to the stability of the adducts which the compounds form withthe amide employed. Also, it is within the scope of my invention for themixture of organic compounds being fractionated to contain compoundsother than those having a single type of carbon atom configuration, asfor example, a C1 to C9 cut from a hydrocarbon mixture containingaromatics, branched-chain hydrocarbons and straight-chain compounds. Inthis situation the non-adduct-forming compounds are removed from theadduct-forming zone in ad mixture with diluent and those less stableadduct-forming fractions removed downstream, with reference to the fiowof liquids, from the point of entry of the original adm'txture.

Figures l and 2 represent schematic diagrams of two embodiments of myinvention. By way of example and without intention of so limiting myinvention, the description of the embodiments shown in Figures l and 2describe the resolution of a mixture of straight-chain hydrocarbonsaccording to their molecular weight using urea as the complex-formingagent.

Referring to Figure l, an admixture of straight carbon atom chainhydrocarbons to be fractionated enters an adduct-forming zone, such ashorizontal column 10, through line l1. Crystalline urea enters column1l) through conduit 12. The urea is present in the system substantiallyin the solid phase and ranges in particle size from 5 to 200 mesh andpreferably 25 to 100. The urea is moved through vessel l0 from its pointof entrance by any suitable mechanical means, such as auger 13, asillustrated, or by means of porous pistons which are so constructed andarranged that the piston heads are pivoted about a diameter thereof insuch a manner that they form porous piston heads across thecross-section of column l0 during the driving stroke thereof and pushthe urea before them and, upon reaction stroke thereof, each half ofsaid piston heads pivot together along said diameter to permit theirretraction through the urea without pulling it back in a direction fromwhence it was just pushed, said piston heads allowing liquids to owfreely therethrough. Column l0 is equipped with a cooling means, such asjacket 14, adapted to cool the urea and/0r any fluids passing throughthe end of the vessel in which the urea is injected. The other end ofcolumn 10 is fitted with heating means, such as jacket l5, adapted toheat any adduct and/or liuids passing through that end. In this manner,fluid passing countercurrently to the moving bed of urea and/or adductin column can act as a heat carrier to maintain a temperaturedifferential across the length of column 10 with the decrease intemperature being in the direction opposite to that of the moving bed.The temperatures at which the cold and hot ends are maintained varydepending upon the mixture being treated and the degree of separationdesired. Generally, the cold end is maintained at a temperature withinthe range of minus 70 to 100 F. and the hot end at a temperature withinthe range of 80 to 270 F. in the case of urea and 8O to 350 F. in thecase of thiourea. As shown in the drawing, the heated end of column 10can be formed to have a wash column 16 into which the crystalline ureais deposited from column 10 by operation of auger 13. According to thisembodiment of the invention, the feed material containing a mixture ofstraightchain hydrocarbons enters horizontal column 10 through line 11,and the cooled end of column 10 in the region of jacket 14 is maintainedat a temperature suiciently low to cause all of the adduct-forminghydrocarbons, or all but a selected fraction of the hydrocarbons, toadduct with urea at that temperature, while the other end of column 10in the region of jacket 15 is maintained at a temperature sufficientlyhigh to cause complete dissociation of any and all adducts formed incolumn 10. As the mixture of straight-chain hydrocarbons introducedthrough line 11 passes into column 10, the longest chain or most readilyadduct-forming fraction or fractions thereof forms an adduct with theurea and is transported by auger 13 toward the hot end of column 10while those fractions which do not form an adduct with urea at thetemperature existing at the point where the mixture is introduced intocolumn 10 pass toward the cooled end of column 10 countercurrently tothe amide and/or adduct moving therethrough. As the adduct moves towardthe hot end of column 10, the more readily dissociated adducts thereinare decomposed to liberate hydrocarbons therefrom, while the most stableadduct remains undissociated until it reaches said hot end, where it isdecomposed. Thus, the longest chain or most stable adductforminghydrocarbons are removed from column 10 via line 17 and passed tofractional distillation zone 18 wherefrom they are removed as a separatefraction through line 19.

A liquid diluent, such as a low-boiling hydrocarbon, or any fluid whichis readily separable from the hydrocarbons being fractionated, and inertto urea at the conditions prevailing, is preferably passed into thesystem through line 20 and thence to wash column 16 to pass upwardlytherethrough countercurrently to the descending column of liberatedurea. Suitable substances which may be used as diluent include butane,n-pentane, isopentane, n-hexane, isohexane, 3-methyl pentane,2,2-dimethyl pentane, 2,2-dimethyl butane, etc. The diluent should bejudiciously chosen depending upon the mixture of compounds beingtreated. A portion of this diluent passes out through line 17 with someof the liberated hydrocarbon, and activator if used, to be separated infractional distillation zone 18 and returned to the system via line 21.If the boiling point of the activator, when used, is near to that of thediluent so that separation from the diluent is not feasible, it may berecycled along with the diluent. The remaining portion of diluent liowsthrough column 10 countercurrently to the urea or adduct containedtherein and is removed through line 22 with the fraction of hydrocarbonswhich does not form an adduct with urea under the conditions employed incolumn 10. In so owing the diluent enhances the transfer of heat alongcolumn 10 while transporting hydrocarbons toward the cold end of thecolumn.

As stated, the liberated urea passes downwardly from the hot end ofcolumn 10 to a washing zone such as wash column 16 wherein it iscontacted with diluent from line 20 thereby being washed free from anyoccluded impurities, such as the hydrocarbons contained in column 10.The condensed diluent from fractional distillation zone 18 as it tirstcontacts the liberated urea is usually at a temperature sutl'icientlylow to help cool the recycle urea before admitting it to the coolinfluent end. After leaving wash column 16, the liberated urea passesthrough a discharge mechanism, such as star valve 23, into a solidtransporting device, such as elevator 24, and is returned to conduit 12and the cooled end of vessel 10. Elevator 24 may be an air lift whichhelps cool the urea further by evaporating occluded diluent.

Intermediate fractions of the mixture introduced into column 10 can bewithdrawn through lines 25 and 26 along with a portion of the diluentpresent at those points in the column. The diluent can be readilyseparated from these removed fractions by ordinary fractionaldistillation as hereinbefore described and can be returned, if desired,to line 20 for further use in the process.

In a second embodiment of my invention the entire reaction zone is keptat a temperature below the dissociation temperature of the adductsformed, preferably below F. Reux hydrocarbon and diluent (and activatorif employed) are cooled before entering the reaction zone. Urea inquantity sul'cient to react wiith only a portion of the mixture ofstraight-chain hydrocarbons is circulated through the system. Figure 2is a schematic diagram of a second embodiment as above-mentioned.

Referring now to Figure 2, the admixture of straightchain hydrocarbonsto be fractionated enters a reaction zone, such as horizontal column 40,through line 41. Crystalline urea at a temperature below thedissociation temperature of any adduct formed and in insuflicientquantity to react with all the straight-chain hydrocarbon, enters column40 at the inliuent end through conduit 42. The urea is moved throughcolumn 40 from its point of entrance by any suitable mechanical means,such as auger 43 as illustrated, or by means of porous pistons as described in the lirst embodiment. As adduct formation is slightlyexothermic, column 40 may be equipped with means (not shown) to cool itbelow the dissociation temperature of any adduct formed. The feedmaterial of this embodiment is the same as that described in the rst. Asthis admixture of straight-chain hydrocarbons introduced through line 41passes into column 40, the most readily adduct-forming fraction orfractions thereof forms an adduct with urea and displaces anyhydrocarbon of fewer carbon atoms from adduct and is transported byauger 43 toward the effluent end of the column, while those fractionswhich have been displaced and for which there is insufficient urea passtoward the influent end of the column. The displaced hydrocarbon acts asinternal reliux and in turn displaces any adducted hydrocarbon of fewercarbon atoms, thus providing a continuous rectitication. When the adductof the longest chain fracA tion reaches the efiiuent end of column 40 itpasses through star valve 44 into decomposing zone 45 which is heated byany conventional means, such as heating jacket 46, above thedissociation temperature of the adduct. The regenerated urea is moved tothe opposite end of the decomposition zone by suitable mechanical means,such as auger 47, and then into washing zone 48 where it is washed witha countercurrently owing stream of diluent, such as described in thefirst embodiment. The diluent passes from washing zone 48 throughdecomposing zone 45 countercurrently to the urea and together with theliberated hydrocarbon passes through line 49 to fractional distillationzone 50. A portion of the liquid effluent from decomposition zone 45 ispassed as reux through line 5l and after cooling in heat exchanger 52back into column 40. The diluent is usually recovered as distillate fromzone 50, a portion of which goes through line 53 and heat exchanger 52to column 40. This portion together with reliux paratiin moves throughcolumn 40 countercurrently to the flow of adduct. If necessary a pumpmay be employed to accomplish the oountercurrent iiow. The other portionof the diluent goes through lines 54 and 5S and is used as wash fortheurea. As mentioned in 'the trst embodiment, the condensed dlluent isusually at a suiciently low temperature to help cool the recycle urea tooperating temperatura. The urea leaving the bottom of the washing zonepasses through star valve S8 and if necessary is cooled in heatexchanger 59 to the operating temperatnreof column 40. From there ispasses to a transporting device, such as elevator 6u.

`when: it is carried to conduit 42 tuttiv deposited in the in ducal endof column 40. Elevator 60 may be any ol the conventional lifting means.As hereinbefore stated, it is advantageous to employ a gas litt whichconcomitantly lifts the urea and evaporates some occluded dilucnt thushelping to cool the urea to operating temperature, as well as removingsome of the diluent which would ordinarily he carried over withshortest-chain hydrocarbon or raffinate through line 6l, The vapolizeddiluent can be condensed and returned to the system.

The longest-chain toms from fractional distillation zone 50 through line56. That fraction for which there was insuicient urea' is recovered,admired with diluent, through line 6I at the influent end of column 40.Il' desired, intermediate fractions of the mixture of straight-chainhydrocarbons introduced into column 40 can be withdrawn through lines 62and 63 along with a portion of the diluent present at those points inthe column. The diluent can he readily separated trom these intermediatefractions by ordinary fractional distillation and can be removed, `il.'desired, to ine 55 for further use in the process. If an activator isemployed in the process, it may he admitted into the sys tem admixedwith the diluent or with the hydrocarbon feed, or with the urea.

ln carrying out the process of my invention one skilled in the arl willappreciate that such things as the degree of separation and productpurity will depend upon such factors as the nature of the feed material.feed rate, amide circulation ritter, length ci the column, redux rale,operating temperatures, the point at which feed or reilux enters thecolumn, etc. The solution of these problems is con.

Vsidered within the skill ol' the art.

While my invention has been described in terms of preferred embodimentsthereof, it is to be understood that this description is illustrativeonly and is not intended ro limit the invention, the scope of which isdened by the claims. Y

l claim:

l. A process for fractonating into at least two fractions a mixture oforganic compounds from the group consisting of a mixture of C: to Csostraight chain organic compounds and a mixture of Cs lnoCss branchedchain organic compounds, at least two of the compounds in said mixturebeing capable of forming a solid adduct with an amide selected from thegroup consisting of urea and thiourea, which comprises continuouslymoving by positive displacement from an inhuent end solid amideaggregated into a mass through an adduot-forming zone, con tinuouslyfeeding the mixture to be fractionated to said zone at a pointintermediate the influent and eiliuent ends thereof to contact saidmoving mass of amide, continuously decomposing less stable solid adductformed as it moves toward the cflluent end of said zone whereby the lessstable adduct is substantially completely eliminated from the eliluentadduct, continuously passing a liquid diluent easily separable trom theseveral fractions and inert to the amide at the conditions existing insaid zone through said zone countercurrently to the How of solids.continuously removing eiiiuent from said eflluent end, continuouslyseparating said effluent into solid amideand diluent admired with thefraction which forms more stable adducts with the amide employed,continuously separating diluent from said admixturc, continuouslywashing the amide separated from said ellluent free from occludcdhydrocarbon isrecovered as botorganic compound with liquid diluent,continuously passmg said diluent from said washing operation to theeiiinent end ot' said adduct-torming zone, continuously recycling saidwashed amide to the inuent end of said stone, continuously removingliquid diluent from said influent end admitted' with the fraction whichforms less stable adducts with the amide employed, continuouslyseparating dilucnt from said admixture, and. recovering the fractionwhich forms the less stable adduct with tite umide employed.

2. A process for iractionating into nt leest two fractions a mixture oforganic compounds selected from the group consisting of a mixture of Csto Cre straight chain organic compounds and a mixture of Cr to Csobranched chain organic compounds, at least two of the con-.pounds insaid mixture lacing capable of forming a solid adduct with an amitieselected from the group consisting of urea and thiourea, which comprisescontinuously moving by positive displacement from an influent end solidtimide aggregated into a mass through an adductforming zone, maintainingthe influent end of said zone at a temperature to forni adducts of atleast two of said organic compounds, maintaining the cllucnt end of saidzone above the decomposition temperature of any sdducts fonned,continuously passing said mixture to said zone at a point intermediatethe nuent and elirent ends. continuously passing through said zone fromsaid effluent end countercurrently to the llow of solids a liquiddiluent easily separable from the several fractions and inert to theamide at the conditions existing in said zone. continuously removingseparately from said eiliuent end solid amide and liquid diluent admixcdwith a fraction which forms more stable adducts with tne amide employed,con tinuously separating dilucnt from said admixture, continuouslypassing said solid amide removed from the eiilucnt cnd of theadduct-forming zone to a washing zone where it is washed with liquiddiluenl, continuously pass ing the liquid eillucnt from said washingzone to the etlluent end of said adduct-torming zone, continuouslycooling and recycling said washed amide to the lnuent end oi saidadduct-formlng zone, continuously ,removing from said influent endliquid diluent admixed witha iractinn which forms less stable adductswith the amide employed, continuously removing at points intermediatethe influent and ethucnt ends of said adduot-formiag zone liquidmixtures of diluent and fractions which form adducts ot intermediatestability. separating diluent from cach of said admixtures andrecovering various fractions of the original mixture of organiccompounds.

3. A proce/.n4 according to claim 2 in which the mixture of organiccompounds is a mixture of C: to Cun straight chain compounds and theamide is uren 4. A process according to claim 2 in which the mixture oforganic compounds is a mixture of Cs to Cen branched chain compounds andthe amide is thiourea.

5. A process according to claim 2 in whichlhc mixture oi' organiccompounds is a mixture of C; lo Css straight chain hydrocarbons and theamide is urea.

6. A process according to claim 2 in which the mixture of organiccompounds is a mixture of Cs to Ctr branched chain hydrocarbons and theamide is thiourca.

7. A process for fractionating a mixture of Cs to Cso straight chainhydrocarbons, at least two of which are capable of fomting an ndductwith urea, into various fractions thereof which comprises continuouslymoving by positive displacement from an inlluent end solid urea ofparticle size within the range of 5 lo 200 mesh aggro gated into a massthrough an addotti-forming zone, maintaining thc inucnt end of said zoneat a temperature in the range of minus to EGOP., maintaining the euentend of said zone at a temperature in the rance of to 270'F.,continuously paming said mixture of straightchain hydrocarbon to saidzone at a point intermediate the influent and clucnt ends. continuouslypassing through said zone from said cfuent end countcrcurrently to themoving solids liquid isopentane, continuously removing separately fromsaid effluent end solid urea and liquid isopentane admixed with thelonger-chain hydrocarbons, continuously separating isopentane from saidadmixture, continuously passing the urea removed from the eluent end ofthe adduct-forming zone to a washing zone where it is washed with liquidisopentane, continuously passing the liquid efuent from said washingzone to the eluent end of said adduct-forming zone, continuously coolingand recycling said washed urea to the inlluent end of saidadduct-forming zone, continuously removing from said influent end liquidisopentane admixed with the shorterchain hydrocarbons, continuouslyremoving at points intermediate the influent and effluent ends of saidadductforming zones liquid admixtures of isopentane and straight-chainhydrocarbons of intermediate-length chain, separating isopentane fromeach of said admixtures and recovering various fractions of the originalmixture of straight chain hydrocarbons.

8. A process for fractionating a mixture of organic compounds selectedfrom the group consisting of a mixture of C3 to Cso straight chainorganic compounds and a mixture of Cs to Cso branched chain organiccompounds, at least two of the compounds in said mixture being capableof forming a solid adduct with an amide selected from the groupconsisting of urea and thiourea, into various fractions thereof whichcomprises continuously moving by positive displacement from an inuentend solid amide aggregated into a mass in quantity insufficient to reactwith all of said organic compounds through an adduct-forming zone,maintaining said zone at a temperature to form adducts of at least twoof said organic compounds, continuously passing said mixture to saidzone at a point intermediate the intuent and eluent ends, continuouslypassing through said zone from said eflluent end countercurrently to theflow of solids a liquid diluent easily separable from the severalfractions and inert to the amide at the conditions existing in said zoneand reux organic compounds, continuously removing from said efluent endsolid adduct, passing said adduct to a decomposition zone, continuouslyremoving from said decomposition zone solid amide and passing same to awashing zone, continuously washing said solid amide with liquid diluentand passing the liquid euent from said washing zone to saiddecomposition zone, continuously removing from said decomposition zoneliquid diluent admixed with the fraction forming more stable adductswith the amide employed, continuously separating from said admixtureliquid diluent, continuously cooling to the proper temperature andrecycling said Washed amide to the iniluent end of said adduct-formingzone, continuously removing from said inlluent end of saidadduct-forming zone liquid diluent admixed with the fraction which formsless stable adducts with the amide employed, continuously removing atpoints intermediate the inlluent and elluent ends of said adduct-formingzone fractions in the liquid phase which form adducts of intermediatestability with the amide employed, continuously separating from each ofsaid admixtures diluent and recovering therefrom various fractions ofthe orginal mixture of organic compounds.

9. A process according to claim 8 in which the mixture of organiccompounds is a mixture of Ca to Cso straight chain compounds and theamide is urea.

10. A process according to claim 8 in which a mixture of organiccompounds is a mixture of C5 to C50 branched chain compounds and theamide is thiourea.

1l. The process according to claim 8 in which the mixture of organiccompounds is a mixture of C3 to Cso straight chain hydrocarbons and theamide is urea.

l2. A process according to claim 8 in which the mixture of organiccompounds is a mixture of C5 to C50 branched chain hydrocarbons and theamide is thiourea.

13. A process for fractionating a mixture of C3 to C50 straight chainhydrocarbons, at least two of which are capable of forming a solidadduct with urea, into various fractions thereof which comprisescontinuously moving by positive displacement from an influent end solidurea aggregated into a mass and in particle size Within the range of 5to 200 mesh and in quantity insuicicnt to react with all of saidstraight-chain hydrocarbons through an adduct-forming zone, maintainingsaid adduct-forming zone at a temperature Within the range of minus to100 F., continuously passing said mixture of hydrocarbons to said zoneat a point intermediate the influent and effluent ends, continuouslypassing through said zone from said eluent end countercurrently to thelow of solids isopentane, continuously removing from said eluent endsolid adduct and passing said solid adduct to a decomposition zone,maintaining said decomposition zone at a temperature within the range ofto 270 F., continuously removing from said decomposition zone solid ureaand passing said urea to a washing zone, continuously washing said ureawith liquid isopentane, continuously passing the liquid eluent from saidwashing zone to said decomposition zone, continuously removing from saiddecomposition zone liquid isopentane and the longer-chain hydrocarbons,continuously cooling to the proper temperature and passing a portion ofsaid admixture to the efluent end of said adduct-forming zone to act asreux, continuously separating isopentane from the other portion of saidadmixture, continuously cooling to the proper temperature and recyclingto the influent end washed solid urea, continuously removing from theintluent end of said adduct-forming zone isopentane admixed with theshorter-chain hydrocarbons, continuously removing at points intermediatethe inuent and eiuent ends of said zone hydrocarbons ofintermediate-length chain in the liquid phase, continuously separatingfrom each of said admixtures isopentane and recovering the variousfractions of the original mixture of straight-chain hydrocarbons.

References Cited in the file of this patent UNITED STATES PATENTS2,386,366 Storment Oct. 9, 1945 2,499,820 Fetterly Mar. 7, 19502,540,977 Arnold Feb. 6, 1951 2,557,257 Melrose June 19, 1951 2,577,202Lien et al. Dec. 4, 1951 2,588,602 Adams et al Mar. 11, 1952 2,640,051Lynch May 26, 1953 OTHER REFERENCES Australian application 17339/ 47,available April 16, 1948 (24 pages spec., now dwg).

1. A PROCESS FOR FRACTIONATING INTO AT LEAST TWO FRACTIONS A MIXTURE OFORGANIC COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF A MIXTURE OF C3TO C50 STRAIGHT CHAIN ORGANIC COMPOUNDS AND A MIXTURE OF C5 TO C50BRANCHED CHAIN ORGANIC COMPOUNDS, AT LEAST TWO OF THE COMPOUNDS IN SAIDMIXTURE BEING CAPABLE OF FORMING A SOLID ADDUCT WITH AN AMIDE SELECTEDFROM THE GROUP CONSISTING OF UREA AND THIOUREA, WHICH COMPRISESCONTINUOUSLY MOVING BY POSITIVE DISPLACEMENT FROM AN INFLUENT END SOLIDAMIDE AGGREAGATED INTO A MASS THROUGH AN ADDUCT-FORMING ZONE,CONTINUOUSLY FEEDING THE MIXTURE TO BE FRACTIONED TO SAID ZONE AT APOINT INTERMEDIATE THE INFLUENT AND EFFLUENT ENDS THEREOF TO CONTACTSAID MOVING MASS OF AMIDE, CONTINUOUSLY DECOMPOSING LESS STABLE SOLIDADDUCT FORMED AS IT MOVES TOWARD THE EFFLUENT END OF SAID ZONE WHEREBYTHE LESS STABLE ADDUCT IS SUBSTANTIALLY COMPLETELY ELIMINATED FROM THEEFFLUENT ADDUCT, CONTINUOUSLY PASSING A LIQUID DILUENT EASILY SEPARABLEFROM THE SEVERAL FRACTIONS AND INERT TO THE AMIDE AT THE CONDITIONSEXISTING IN SAID ZONE THROUGH SAID ZONE COUNTERCURRENTLY TO THE FLOW OFSOLIDS, CONTINUOUSLY REMOVING EFFLUENT FROM SAID EFFLUENT END,CONTINUOUSLY SEPARATING SAID EFFLUENT INTO SOLID AMIDE AND DILUENTADMIXED WITH THE FRACTION WHICH FORMS MORE STABLE ADDUCTS WITH THE AMIDEEMPLOYED, CONTINUOUSLY SEPARATING DILUENT FROM SAID ADMIXTURE,CONTINUOUSLY WASHING THE AMIDE SEPARATED FROM SAID EFFLUENT FREE FROMOCCLUDED ORGANIC COMPOUND WITH LIQUID DILUENT, CONTINUOUSLY PASSING SAIDDILUENT FROM SAID WASHING OPERATION TO THE EFFLUENT END OF SAIDADDUCT-FORMING ZONE, CONTINUOUSLY RECYCLING SAID WASHED AMIDE TO THEINFLUENT END OF SAID ZONE, CONTINUOUSLY REMOVING LIQUID DILUENT FROMSAID INFLUENT END ADMIXED WITH THE FRACTION WHICH FORMS LESS STABLEADDUCTS WITH THE AMIDE EMPLOYED, CONTINUOUSLY SEPARATING DILUENT FROMSAID ADMIXTURE, AND RECOVERING THE FRACTION WHICH FORMS THE LESS STABLEADDUCT WITH THE AMIDE EMPLOYED.